(1) Field of the Invention
The present invention relates to an image display apparatus such as a television receiver, and more particularly to an image display apparatus comprising an image processing circuit that detects characteristics of an input image signal to correct the grayscale thereof.
(2) Description of the Related Art
For example, Japanese Patent Laid-Open No. Hei 8-317250 (patent document 1) and Japanese Patent Laid-Open No. 2000-307896 (patent document 2) disclose techniques used to improve the impression of contrast. These techniques are used for, for example, display units for displaying images.
The patent document 1 discloses the technique in which a luminance histogram and an average luminance level (it might be called an Average Peak Level or Average Picture Level, hereinafter referred to as “APL”) are calculated from an input image signal, and thereby a gamma curve used for gamma correction is set by use of the luminance histogram and the APL.
The patent document 2 discloses the technique in which an area characterized by the high frequency in a luminance histogram is calculated from an input image signal, and thereby a luminance-value correction parameter is calculated in response to the frequency of the area to set a gamma curve.